It is understood that the company hired Generation because of its expertise in targeting young people. The agency takes control of the account from July 1. Carat has held the account for the past two years. Infogrames' - now Atari's - creative agencies are Red Pepper and A Creative Experience.
The appointment comes as the firm prepares for its biggest release of the year, Enter The Matrix, which is available from today (Thursday).
Infogrames bought the rights to the Atari brand two years ago through its acquisition of Hasbro's interactive games division for £71.7m.
The company changed name last week after deciding the Atari name had more recognition and kudos than the Infogrames brand, which has struggled against the likes of Electronic Arts and Eidos.